diff --git a/radio/src/simu.cpp b/radio/src/simu.cpp
index 3f33e4dde..89996d406 100644
--- a/radio/src/simu.cpp
+++ b/radio/src/simu.cpp
@@ -635,7 +635,9 @@ int main(int argc, char ** argv)
   startEepromThread(argc >= 2 ? argv[1] : "eeprom.bin");
 #endif
 
+#if !defined(SIMU_BOOTLOADER)
   startAudioThread();
+#endif
   simuStart(true/*false*/, argc >= 3 ? argv[2] : 0, argc >= 4 ? argv[3] : 0);
 
   return application.run();
diff --git a/radio/src/targets/simu/simufatfs.cpp b/radio/src/targets/simu/simufatfs.cpp
index e8737e328..e7551adc8 100644
--- a/radio/src/targets/simu/simufatfs.cpp
+++ b/radio/src/targets/simu/simufatfs.cpp
@@ -469,11 +469,15 @@ FRESULT f_readdir (DIR * rep, FILINFO * fil)
     if (strcmp(ent->d_name, ".") && strcmp(ent->d_name, "..") ) break;
   }
 
-  memset(fil->fname, 0, FF_MAX_LFN);
-  strcpy(fil->fname, ent->d_name);
-  // TRACE_SIMPGMSPACE("f_readdir(): %s", fil->fname);
-  std::string fullName = sd->name + std::string("/") + std::string(ent->d_name);
-  return f_stat(fullName.c_str(), fil);
+  if (fil != nullptr) {
+      memset(fil->fname, 0, FF_MAX_LFN);
+      strcpy(fil->fname, ent->d_name);
+      // TRACE_SIMPGMSPACE("f_readdir(): %s", fil->fname);
+      std::string fullName = sd->name + std::string("/") + std::string(ent->d_name);
+      return f_stat(fullName.c_str(), fil);
+  }
+
+  return FR_OK;
 }
 
 FRESULT f_mkfs (const TCHAR* path, BYTE opt, DWORD au, void* work, UINT len)